Movable fulcrum for springboards



March 12, 1968 R. c. RUDE MOVABLE FULCRUM FOR SPRINGBOARDS 2 Sheets-Sheet 1 Filed Sept. 24, 1965 if 45 f7 March 12, 1968 R. c. RUDE 3,372,927

MOVABLE FULCRUM FOR SPRINGBOARDS Filed Sept. 24, 1965 2 Sheets-Sheet 2 Q v i g INVENTOR.

; emmw a 21/05 BY United States Patent Ofilice 3,372,927 MOVABLE FULCRUM FOR SPRINGBOARDS Raymond C. Rude, 2468 Wagner, Pasadena, Calif. 91107 Filed Sept. 24, 1965, Ser. No. 490,050 8 Claims. (Cl. 272--66) This invention relates to supports for springboards. More particularly, it provides a movable fulcrum for location between the fixed and unsupported ends of a diving or springboard.

My United States Patent No. 3,072,401, issued Jan. 8, 1963, describes a movable fulcrum mechanism for use with springboards of the type used in diving. Movable fulcrums have utility with such springboards since they provlde a means whereby a particular diver can match the resonant frequency of the diving board to the rhythms of his stride and take-off, thereby allowing the diver to obtain the best possible spring from the board.

While devices in accord with Patent No. 3,072,401 fill a need not filled by any previous devices and they are usually fully effective to perform the functions intended for them, it has been found that such devices occasionally present certain probiems in use, particularly when they have been in use for some time. These problems are attributable principally to the effects of corrosion and of foreign particles on the bearing surfaces along which move the rollers which support the frame to which a diving board engaging drum is mounted. The drum is driven by a diver against the underside of the board to move the frame along bearing surfaces lengthwise of the board. When foreign particles are present on the bearing surfaces, the diver may find it dilficult to drive the rollers over them. The same disadvantageous effect is produced when the bearing surfaces or the rollers become corroded, as by salt air, or when the rollers bind on their axles because of the formation of corrosion products on and around the axles.

This invention provides a movable fulcrum structure which has a simplified construction over devices built in accord with the teachings of my prior patent. Also, the present movable fulcrum incorporates means for wiping the surfaces along which the fulcrum moves free of foreign particles. Moreover, all relatively movable components of the fulcrum are separated from each other by non-conductive material, thereby preventing electrolytic corrosion of these components in the presence of moist salt air.

Generally speaking, this invention provides a movable support for a load-bearing article. The movable support includes cylindrical rotatable means engageable with the underside of the article for supporting the article. Cradle means are provided for rotatably mounting the rotatable means transversely of the article. Guide way means are provided for supporting the cradle means and for accom modating and guiding movement of the cradle means. Slide bearing means are provided on the cradle means and are slidably engaged with the guide way means. The support also includes operating means connected to the rotatable means for rotation therewith for rotating the rotatable means against the article to displace the rotatable means and the cradle means along the article to change the location of article support by the rotatable means. i

The above mentioned and other features of this invention are more fully set forth in the following detailed description of a presently prefer-red embodiment of the invention, the description being presented with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a movable fulcrum mechanism according to this invention;

3,372,927 Patented Mar. 12, 1968 FIG. 2 is a transverse cross-sectional elevation View of the fulcrum mechanism shown in FIG. 1; and

FIG. 3 is a cross-sectional elevation view taken along line 3-3 of FIG. 2.

The movable fulcrum provided by this invention is illustrated and described in conjunction with an all-metal springboard illustrated more completely in my United States Patent No. 2,864,616, issued Dec. 16, 1958. Also, the fulcrum is described in conjunction with an improved foundation. It is to be understood, however, that the fulcrum can be used advantageously with springboards and foundations different from those illustrated and described without departing from the scope of this invention.

Referring to FIG. 1, a movable fulcrum 10 according to this invention is shown engaged with a foundation unit 11 which is mounted to the upper end of a diving board support pedestal 12. A divers springboard or diving board 13, preferably constructed in accord with the teachings of my US. Patent No. 2,864,616, is engaged with the movable fulcrum intermediate its ends. The diving board is disposed so that its elongate extent is transverse to the elongate extent of the fulcrum mechanism. The springboard has one end thereof hingeably connected to a springboard support (not shown). The other end of the springboard is unsupported.

As shown best in FIGS. 2 and 3, fulcrum 10 includes an elongate, circularly cylindrical and preferably hollow drum 15. A plurality of substantially reotangularly crosssectioned ribs or flutes 16 extend radially from the exterior surface of the drum. The flutes are aligned parallel to the axis of the drum so that the drum has a smooth, circularly cylindrical portion 17 circumferentially of its midlength. Also, the ends of the ribs adjacent the ends of the drum lie a predetermined distance inwardly from the drum ends so that, adjacent its opposite ends, the exterior of the drum defines smooth, circularly, cylindrical portions 18. The drum has a length greater than the Width of diving board 13; drum portions '18 of the drum are disposed outwardly of the sides of the diving board. A shaft 19 extends coaxially from and. .is fixed to one end of the drum. An operating wheel 20 is secured to shaft 19 at a location spaced from the drum. A 'diver standing on the board over the drum may engage the wheel with his foot to rotate the wheel to rotate the drum and drive the drum against the bottom of the board. The wheel is provided with raised ribs 21 around its periphery so that the divers foot will not slip against the surface of the wheel.

A pair of parallel ways or rails 24 are mounted to the fulcrum foundation. The rails each have horizontal upper surfaces 25. One of the rails also has opposite vertical and parallel side surfaces 26; preferably both rails are identical. The rails are aligned parallel to the length of the diving board and are spaced apart a distance less than the distance between drum portions 18. Preferably, as shown in FIG. 2 the rails are mounted to the upper surfaces of a pair of aligned opposing flanges 27 which extend inwardly from the foundation side walls 28. It is preferred that the foundation define an upwardly open recess extending laterally to beneath the rails.

The drum is supported in an elongate box-like cradle or frame 34 having an open upper side 31, forward and rear side walls 32, a substantially closed bottom 33, and end walls 34. The frame has a length slightly greater than the length of the drum. The end walls of the frame define semi-circular, upwardly open, coaxially aligned recesses 35. A raised rib-like land 36 projects from the wall of each recess toward the center of the recess; each land extends along the entire semi-circular extent of the recess. A strip of tetrafluoroethylene plastic, or some other material which has a similar low coeflicient of friction relative to the material (preferably aluminum) from which the drum is fabricated, is bonded to the surface of each land along its entire extent. The concave surfaces of the tetrafluoroethylene strips mate with drum portions 18 so that the drum is rotatably mounted in the frame at its opposite ends. An inelastic band 38, preferably defined by a Whittee hose clamp, is secured to the upper surface of the frame bottom below drum portion 17 by bolts 46 passed through the frame. The band extends continuously upwardly around drum portion 17 back to the frame as shown in FIG. 3. A strip 39 of tetrafiuoroethylene plastic or the like is disposed between the band and drum portion 17. The band is tensioned so that the tetrafiuoroethylene strip is intimately engaged with the drum over a major portion of the circumference of the drum and holds the drum in engagement with the frame.

A downwardly open, rectangular recess or groove 42 is formed in the underside of the frame bottom adjacent each end of the frame. The grooves are parallel to one another and are spaced apart a distance corresponding to the spacing between rails 24. The grooves are aligned normal to the axis of the drum. Each groove has a central enlarged portion 43 (see the groove at the right end of the frame in FIG. 2) and, between its ends and the enlarged portion, is wider than the width of the adjacent rail.

A strip 44, 45 of tetrafluoroethylene plastic or similar material is secured to the upper surface of each groove along its entire length. The tetrafluoroethylene strip 44, engaged in the groove at the right end of the frame (see FIG. 2), extends across the upper surface of the groove, but not along the side walls of the groove. Thus, a clearance is provided between the side walls of the groove and the side walls of the rail disposed in the groove. Strip 45, engaged in the groove at the left end of the frame, extends across the upper surface of the groove and also along the side walls of the groove to mate intimately with the side walls of the rail disposed in the groove. Strips 44 and 45, to the extent they extend across the upper surfaces of their grooves, define rail engaging shoes for slidably mounting frame to rails 24. Further, since strip 45 extends into engagement with the side walls of the left rail, this shoe serves to guide movement of the frame along the rails. Shoe 45 is sufficiently long to prevent the frame from being cocked relative to the rails. Also, the shoes provide means for wiping the rails clean of any foreign particles thereon as the frame is moved along the rails.

It is preferred that the drum and the frame be fabricated of aluminum, and that the rails be fabricated of hard anodized aluminum. The rails, however, are separated from the frame by the non-conductive tetrafluoroethylene shoes; similarly, the drum is separated from the frame by a non-conductive material. Accordingly, any corrosion of the drum, frame and rails is minimized and relative movement between these elements in response to rotation of the drum is assured over an extended period, even under adverse weather conditions.

The fulcrum also includes means for lubricating the surfaces along which slidable motion occurs. As shown in FIG. 2, each tetrafluoroethylene strip 37, at the bottommost portion of its extent around the drum, is provided with an opening 47. Each opening communicates with a passage 48 formed in the lower portion of the base adjacent each of its ends. Each passage also communicates with an opening (not shown) formed through the portion of the respective one of shoes 44 and 45 in the enlarged portion of the groove adjacent the passage. Each passage is filled with a wick material, such as felt, which is impregnated with lubricating oil. Accordingly, the surfaces along which occur slidable motion between the frame and the drum, and between the frame and the rails, are continuously lubricated. Thus, the fulcrum, so long as the wicks are impregnated with oil, is easily movable along the foundation and the drum is freely rotatable in the frame.

A doubly cantilevered leaf spring 55, i.e., a leaf spring supported only at its center and not at its opposite ends, is secured to the underside of the frame by bolts 40. Each end of the spring defines an upwardly opening U-shaped wheel holder 56 below foundation flanges which mount the rails. A wheel 57, preferably fabricated of phenol-formaldehyde resin or the like, is rotatably mounted between the vertical legs of each holder by an axial pin 58 passed through the parallel legs of the holder. The spring is biased so that the wheels are urged into engagement with the undersides of the foundation flanges. Accordingly, the frame is continuously urged downwardly into engagement with the rails. The spring, therefore, provides a means for preventing bouncing or slapping of the frame on the rails as the diving board is used.

The diving board is provided with friction inducing means along its underside in the vicinity of the fulcrum to assure that the coeffieient of friction between the drum an the board is higher than the coefficient of friction which exists between the frame and the rails, thereby assuring that rotation of the drum against the bottom of the board will roduce movement of the frame along the rails. As indicated above, this invention is most preferably practiced with a diving board fabricated according to the disclosures of US. Patent No. 2,864,616. In such a case, the friction inducing means are provided in the form of rubber shoes 60 which are engaged over the lower ends of the bulbed ribs 61 which extend from the underside of the board. In the event, however, that springboard is not fabricated in accord with this patent, the friction inducing means may be provided in the form of a rubber sheet or the like glued or bonded to the underside of the springboard.

Fulcrum 10 has several advantages over fulcrums disclosed in my prior Patent 3,072,401. Fulcrums in accord with this prior patent include a rotatable drum which has a roughened surface engageable with rubber shoes or the like secured to the underside of a diving board. As such fulcrums are operated, the roughed surface of the drum often causes particles of rubber to be abraded from the rubber shoes; these particles fall upon the rails along which move the rollers which support the frame of such a fulcrum, These rubber particles, together with other foreign particles such as leaves, twigs and the like, impede movement of the rollers along the rails and cause the drum to slip relative to the underside of the diving board. These disadvantages are not encountered when fulcrum 10 is used since drum ribs 16 provide positive traction against shoes 60 or their equivalent without causing particles to be abraded from the shoes. Moreover, the use of non-metallic shoe-type rail engaging hearings to mount the frame of fulcrum 10 to the rails assures continuous cleaning of the rails as the fulcrum is operated. Also, fulcrum 10 is considerably simpler to construct than a fulcrum constructed in accord with the above-mentioned patent. All these advantages contribute to long trouble-free operation of fulcrum 10. Further more, servicing of the fulcrum may be accomplished simply and without any special tools.

While the invention has been described above by reference to a presently preferred embodiment of the invention, workers skilled in the art will appreciate that modifications and alterations may be made in the structure described without departing from the scope of this invention. Accordingly, it is to be understood that the foregoing description has been presented essentially for the purposes of example and illustration and is not to be regarded as limiting the scope of this invention.

What is claimed is:

1. A movable fulcrum for a springboard having a supported end and an unsupported end, the springboard being disposed over a support located below the springboard intermediate the ends thereof, the support providing a pair of horizontal rectangularly cross-sectioned parallel rails spaced transversely of the springboard and aligned with the length of the springboard, the fulcrum comprising a frame adapted to be supported on the rails and including a rail enga ing shoe slidably engageable with each rail, means for guiding movement of the frame along the rails, a drum engaging the underside of the springboard, means rotatably mounting the drum to the frame transversely of the springboard, means connected to the drum operable by a person on the springboard over the drum for rotating the drum to drive the drum against the springboard thereby to move the drum along the springboard, wherein said frame comprises an upwardly open elongate frame disposed transversely of the rails and having end walls defining upwardly open c0- axially aligned recesses, the means mounting the drum to the frame includes a quantity of material having a low coetlicient of friction relative to the material from which the drum is fabricated secured to the frame in each recess and having upwardly open semi-circularly curved surface conforming to the curvature of the drum and engaging the drum adjacent a respective end thereof and means extending from the frame over the drum at substantially the midlength of the drum for retaining the drum in the frame.

2. A fulcrum according to claim 1 wherein the material disposed in the recess and engaging the drum is principally tetrafiuoroethylene.

3. A fulcrum according to claim 1 wherein the means retaining the drum in the frame comprises an inelastic band extending from the frame below the drum over the drum to the frame, and a strip of tetrafiuoroethylene secured to the hand between the band and the drum in engagement with the drum.

4. A fulcrum according to claim 1 wherein the frame adjacent each end thereof defines a downwardly open groove over each rail extending transversely of the frame, each rail being disposed in a respective one of the grooves, and each groove being wider than the rail disposed therein, a first piece of tetrafluoroethylene disposed in one groove and extending along the length of the groove engaging only with the upper surface of the adjacent rail, and a second piece of tetrafiuoroethylene disposed in the other groove and extending along the length thereof en-- gaging the upper and side surfaces of the adjacent rail along the extent of said piece.

5. A movable fulcrum for a springboard having a supported end and an unsupported end, the springboard being disposed over a support located below the springboard intermediate the ends thereof, the support providing a pair of horizontal rectangularly cross-sectioned parallel rails spaced transversely of the springboard and aligned with the length of the springboard, the fulcrum comprising a frame adapted to be supported on the rails and including a rail engaging shoe slidably engageable with each rail, means for guiding movement of the frame along the rails, a drum engaging the underside of the springboard, means rotatably mounting the drum to the frame transversely of the springboard, means connected to the drum operable by a person on the springboard over the drum for rotating the drum to drive the drum against the springboard thereby to move the drum along the springboard, and a leaf spring for holding said frame in engagement with said rails, said leaf spring secured to the frame between the rails and extending laterally from the connection to the frame to ends disposed below and biased toward the rails, and a wheel rotatably mounted to each end of the spring.

6. A movable fulcrum for a springboard having a su ported end and an unsupported end, the springboard being disposed over a support located below the springboard intermediate the ends thereof, the support providing a pair of horizontal rectangularly cross-sectioned parallel rails spaced transversely of the springboard and aligned with the length of the springboard, the fulcrum comprising a frame adapted to be supported on the rails and including a rail engaging shoe slidably engageable with each rail, means for guiding movement of the frame along the rails, a drum engaging the underside of the springboard, means rotatably mounting the drum to the frame transversely of the springboard, means connected to the drum operable by a person on the springboard over the drum for rotating the drum to drive the drum against the springboard thereby to move the drum along the springboard, and wherein said drum carries, at spaced locations around its circumference, a plurality of ribs extending longitudinally along the drum and radially thereof, the underside of said springboard having friction means thereon for engaging said ribs and moving said fulcrum relative to the springboard upon rotation of said drum.

7. A movable fulcrum for a springboard having a supported end and an unsupported end, the springboard intermediate its ends being disposed over a support having a pair of horizontally spaced flanges which extend toward each other, the support mounting a pair of rectangularly cross-sectioned horizontal parallel rails spaced transversely of the springboard and aligned with the length of the springboard, the fulcrum comprising an elongate frame having an open top and end walls, disposed transversely of and supported on the rails, the frame through its transverse extent around each rail defining a downwardly open groove into which the adjacent rail extends from the support and having a width greater than the width of the adjacent rail, one of the grooves carrying along the length thereof over the adjacent rail a piece of tetrafluoroethylene slidably engaged only with the top of the adjacent rail, the other groove carrying aiong the length thereof over and along the adjacent rail a piece of tetrafluoroethyleue slidably engaged with the top and sides of the adjacent rail, each frame end wall mounting in a vertical plane parallel to the rails a further piece of tetrafiuoroethylene having an upwardly open surface curved to mate with the curvature of the drum, and means engaged between the drum ribs and the jacent the ends of the drum to be mounted to the frame for rotation about an axis transverse to the rails and to extend upwardly from the frame into engagement with the underside of the springboard, the drum between said further pieces carrying a plurality of spaced substantially rectangularly cross-sectioned ribs extending radially outwardly of the drum and along the drum a Wheel having a diameter greater than the diameter of the drum secured coaxially to one end of the drum, a leaf spring secured substantially at its midlength to the frame below the drum and extending to ends disposed below and biased toward the support flanges, a wheel rotatably mounted to each end of the spring for rolling engagement with the drum,- and means engaged between the drum ribs and the underside of the springboard providing higher friction therebetween than between the first-mentioned pieces of tetrafluoroethylene and the rails so that upon rotation of the wheel the drum is rotated without substantial slippage against the springboard and the frame is moved along the rails to change the position of support of the springboard by the drum.

8. A fulcrum according to claim 7 including means carried by the frame for lubricating the surfaces of said pieces of tetrafiuoroethylene and engaged with the drum and the rails.

References Cited UNITED STATES PATENTS 1,412,699 4/1922 Manchester 3083.8 2,032,574 3/1936 Handley 27266 2,733,972 2/1956 Diack 3683.8 3,008,776 11/ 1961 Love. 3,072,401 1/1963 Rude 272-66 3,089,198 5/1963 Eirhart. 3,125,340 3/1964 Baker 272-66 3,321,204 5/1967 Pretti 272-66 FOREIGN PATENTS 646,883 11/ 1950 Great Britain. 942,163 11/1963 Great Britain.

RICHARD C. PINKHAM, Primary Examiner. 

1. A MOVABLE FULCRUM FOR A SPRINGBOARD HAVING A SUPPORTED END AND AN UNSUPPORTED END, THE SPRINGBOARD BEING DISPOSED OVER A SUPPORT LOCATED BELOW THE SPRINGBOARD INTERMEDIATE THE ENDS THEREOF, THE SUPPORT PROVIDING A PAIR OF HORIZONTAL RECTANGULARLY CROSS-SECTIONED PARALLEL RAILS SPACED TRANSVERSELY OF THE SPRINGBOARD AND ALIGNED WITH THE LENGTH OF THE SPRINGBOARD, THE FULCRUM COMPRISING A FRAME ADAPTED TO BE SUPPORTED ON THE RAILS AND INCLUDING A RAIL ENGAGING SHOE SLIDABLY ENGAGEABLE WITH EACH RAIL, MEANS FOR GUIDING MOVEMENT OF THE FRAME ALONG THE RAILS, A DRUM ENGAGING THE UNDERSIDE OF THE SPRINGBOARD, MEANS ROTATABLY MOUNTING THE DRUM TO THE FRAME TRANSVERSELY OF THE SPRINGBOARD, MEANS CONNECTED TO THE DRUM OPERABLE BY A PERSON ON THE SPRINGBOARD OVER THE DRUM FOR ROTATING THE DRUM TO DRIVE THE DRUM AGAINST THE SPRINGBOARD THEREBY TO MOVE THE DRUM ALONG THE SPRINGBOARD, WHEREIN SAID FRAME COMPRISES AN UPWARDLY OPEN ELONGATE FRAME DISPOSED TRANSVERSELY OF THE RAILS AND HAVING END WALLS DEFINING UPWARDLY OPEN COAXIALLY ALIGNED RECESSES, THE MEANS MOUNTING THE DRUM TO THE FRAME INCLUDES A QUANTITY OF MATERIAL HAVING A LOW COEFFICIENT OF FRICTION RELATIVE TO THE MATERIAL FROM WHICH THE DRUM IS FABRICATED SECURED TO THE FRAME IN EACH RECESS AND HAVING AN UPWARDLY OPEN SEMI-CIRCULARLY CURVED SUFACE CONFORMING TO THE CURVATURE OF THE DRUM AND ENGAGING THE DRUM ADJACENT A RESPECTIVE AND THEREOF AND MEANS EXTENDING FROM THE FRAME OVER THE DRUM AT SUBSTANTIALLY THE MIDLENGTH OF THE DRUM FOR RETAINING THE DRUM IN THE FRAME. 